Neonatal Alloimmune Thrombocytopenia Caused by Anti-HLA-A2 Alloantibodies Determined by Luminex Single Antigen Bead Assay

ABSTRACT

Neonatal alloimmune thrombocytopenia (NAIT) occurs when maternal alloantibodies react to antigens expressed on fetal platelets, which is mainly platelet-specific alloantigen or HLA, resulting in their immune destruction. Here, we described a patient who suffered from NAIT caused by anti-HLA-A2 antibody. Sera from the mother and the newborn were screened for human platelet antigen-specific antibodies and HLA antibodies by ELISA, and HLA antibodies were detected in both of them. The antibody specificity was identified as anti-HLA-A2 by Luminex single antigen bead assay. HLA typing results showed that patient's father descended HLA-A2 antigen on the patient and the mother was HLA-A2 negative. It is most conceivable that anti-HLA-A2 alloantibody in the mother's sera crossed the placenta and subsequently caused NAIT in the case presented. The patient received platelet concentrates, oral steroid and intravenous globulin and platelet count increased to 120x10(9)/L on the 90th day of life. The Luminex single antigen bead assay used in this case is highly sensitive and specific assay to determine antibody specificity and it is faster and more convenient for routine use in clinical laboratory so that this assay could be useful to diagnose NAIT caused by HLA antibodies and treat such NAIT patients with HLA matched platelet transfusion.